One manufacturer has redesigned an automobile ignition switch mechanism and enclosed it and the ignition lock in a plastic housing. The housing includes a protruding lock barrel which surrounds the ignition lock cylinder. An opening in the housing, at one end of the lock barrel, exposes the keyhole end of the lock cylinder. A driver inserts a key into the keyhole to unlock the ignition lock and operate the ignition switch.
A thief must enter the housing to gain access to the switch. Unfortunately, the plastic housing is not tamper-proof and a thief can gain access to the ignition switch either by forceably removing the lock cylinder from the housing through the opening and thereby freeing the switch, or by inserting a screwdriver into the exposed keyhole and forceably rotating the cylinder to unlock and operate the switch.
Various devices have been designed to prevent unauthorized access to the lock cylinder. One such device is described in U.S. Pat. No. 5,063,765 to Squire et al. It comprises a lock barrel protector, having an end cap which fits over the otherwise exposed keyhole end of the cylinder and provides a guarded passageway for the ignition key. A "retaining means," such as a set screw, holds the protector in place. The device slides over and attaches to the lock barrel which surrounds the lock cylinder, with the set screw embedded in the lock barrel to prevent removal of the device.
The Squire et al. device works well with locks having metallic barrels. It does not work well with locks which have plastic barrels, such as the locks described above. To defeat this lock protection device, a thief can puncture the plastic barrel to disable or detach the set screw, and remove the device. The thief then has direct access to the lock cylinder and, ultimately, to the ignition switch.